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72-443: Cygnus X-3 is a prominent X-ray source , with soft and hard X-rays both varying in intensity. Periods where the hard X-rays are at minimum intensity are known as soft states. It is less than half a degree from a gamma-ray pulsar, but is itself a weak gamma-ray source. It also shows periodic gamma-ray flares, apparently all occurring during the soft state. It is undetectable at visual wavelengths due to extreme extinction in

144-414: A 4.8  h period. The nature of the infrared spectrum and the x-ray emission is interpreted as a binary system containing a Wolf–Rayet (WR) star and a compact object. The 4.8 h variations have been interpreted as eclipses, but this is thought to be unlikely because there are not well-defined periodic dips in the brightness. The orbit of the binary system is not known accurately, other than

216-533: A Q uasi- S tellar O bject (QSO) that emits baffling amounts of radio energy. This radio emission is caused by electrons spiraling (thus accelerating) along magnetic fields producing cyclotron or synchrotron radiation . These electrons can also interact with visible light emitted by the disk around the AGN or the black hole at its center. These photons accelerate the electrons, which then emit X- and gamma-radiation via Compton and inverse Compton scattering. On board

288-458: A binary companion . This requires a flow of material sufficiently high to sustain the fusion. Real mass transfer variations may be occurring in V Sge similar to SSXS RX J0513.9-6951 as revealed by analysis of the activity of the SSXS V Sge where episodes of long low states occur in a cycle of ~400 days. HD 49798 is a subdwarf star that forms a binary system with RX J0648.0-4418. The subdwarf star

360-459: A red giant star. The dense white dwarf can accumulate gas donated from the companion. When the dwarf reaches the critical mass of 1.4  M ☉ , a thermonuclear explosion ensues. As each Type Ia shines with a known luminosity, Type Ia are used as " standard candles " to measure distances in the universe. SN 2005ke is the first Type Ia supernova detected in X-ray wavelengths, and it

432-427: A supermassive black hole , which may result in an active galactic nucleus . Galaxies can also have satellites in the form of dwarf galaxies and globular clusters . The constituents of a galaxy are formed out of gaseous matter that assembles through gravitational self-attraction in a hierarchical manner. At this level, the resulting fundamental components are the stars, which are typically assembled in clusters from

504-458: A variable star . An example of this is the instability strip , a region of the H-R diagram that includes Delta Scuti , RR Lyrae and Cepheid variables . The evolving star may eject some portion of its atmosphere to form a nebula, either steadily to form a planetary nebula or in a supernova explosion that leaves a remnant . Depending on the initial mass of the star and the presence or absence of

576-530: A white dwarf ( cataclysmic variable stars and super soft X-ray sources ), neutron star or black hole ( X-ray binaries ). Some Solar System bodies emit X-rays, the most notable being the Moon , although most of the X-ray brightness of the Moon arises from reflected solar X-rays. Furthermore, celestial entities in space are discussed as celestial X-ray sources. The origin of all observed astronomical X-ray sources

648-406: A body and an object: It is a body when referring to the frozen nucleus of ice and dust, and an object when describing the entire comet with its diffuse coma and tail . Astronomical objects such as stars , planets , nebulae , asteroids and comets have been observed for thousands of years, although early cultures thought of these bodies as gods or deities. These early cultures found

720-542: A companion, a star may spend the last part of its life as a compact object ; either a white dwarf , neutron star , or black hole . The IAU definitions of planet and dwarf planet require that a Sun-orbiting astronomical body has undergone the rounding process to reach a roughly spherical shape, an achievement known as hydrostatic equilibrium . The same spheroidal shape can be seen on smaller rocky planets like Mars to gas giants like Jupiter . Any natural Sun-orbiting body that has not reached hydrostatic equilibrium

792-432: A homogeneous, high-gravity, pure hydrogen atmosphere with a temperature near 28,000 K." These observations of PG 1658+441 support a correlation between temperature and helium abundance in white dwarf atmospheres. A super soft X-ray source (SSXS) radiates soft X-rays in the range of 0.09 to 2.5 keV . Super soft X-rays are believed to be produced by steady nuclear fusion on a white dwarf's surface of material pulled from

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864-585: A low mass brown dwarf in a multiple star system. This is the first time that a brown dwarf this close to its parent star(s) (Sun-like stars TWA 5A) has been resolved in X-rays. "Our Chandra data show that the X-rays originate from the brown dwarf's coronal plasma which is some 3 million degrees Celsius", said Yohko Tsuboi of Chuo University in Tokyo. "This brown dwarf is as bright as the Sun today in X-ray light, while it

936-434: A mass of less than about 8% of the mass of the Sun cannot sustain significant nuclear fusion in its core. This marks the dividing line between red dwarf stars and brown dwarfs . The dividing line between planets and brown dwarfs occurs with objects that have masses below about 1% of the mass of the Sun, or 10 times the mass of Jupiter . These objects cannot fuse deuterium. With no strong central nuclear energy source,

1008-460: A sixth magnitude star 3 Cassiopeiae by John Flamsteed on 16 August 1680 ). Possible explanations lean toward the idea that the source star was unusually massive and had previously ejected much of its outer layers. These outer layers would have cloaked the star and reabsorbed much of the light released as the inner star collapsed. CTA 1 is another SNR X-ray source in Cassiopeia . A pulsar in

1080-448: A star made of quarks , but are now explained as being produced in the relativistic jet. The explanation for the unusual relationship between the x-rays and the gamma-ray and radio flares is that the compact objects produces jets along its axis of rotation, within the dense wind from the WR star. These jets evacuate a cocoon within the wind when entering the hard state, and are then quenched by

1152-432: A thousand times more powerful than those on Earth. On Earth, auroras are triggered by solar storms of energetic particles, which disturb Earth's magnetic field. As shown by the swept-back appearance in the illustration, gusts of particles from the Sun also distort Jupiter's magnetic field, and on occasion produce auroras. Saturn's X-ray spectrum is similar to that of X-rays from the Sun indicating that Saturn's X-radiation

1224-426: A web that spans the observable universe. Galaxies have a variety of morphologies , with irregular , elliptical and disk-like shapes, depending on their formation and evolutionary histories, including interaction with other galaxies, which may lead to a merger . Disc galaxies encompass lenticular and spiral galaxies with features, such as spiral arms and a distinct halo . At the core, most galaxies have

1296-416: Is 7.4 ± 1.1 kpc . Astrophysical X-ray source Astrophysical X-ray sources are astronomical objects with physical properties which result in the emission of X-rays . Several types of astrophysical objects emit X-rays. They include galaxy clusters , black holes in active galactic nuclei (AGN), galactic objects such as supernova remnants , stars , and binary stars containing

1368-465: Is a binary star system where one of the components is a neutron star or a black hole. The other component is an intermediate mass star. Hercules X-1 is composed of a neutron star accreting matter from a normal star (HZ Her) probably due to Roche lobe overflow. X-1 is the prototype for the massive X-ray binaries although it falls on the borderline, ~2  M ☉ , between high- and low-mass X-ray binaries. The first extrasolar X-ray source

1440-404: Is a bright object in the optical and UV bands. The orbital period of the system is accurately known. Recent XMM-Newton observations timed to coincide with the expected eclipse of the X-ray source allowed an accurate determination of the mass of the X-ray source (at least 1.2 solar masses), establishing the X-ray source as a rare, ultra-massive white dwarf. According to theory, an object that has

1512-683: Is a naturally occurring physical entity , association, or structure that exists within the observable universe . In astronomy , the terms object and body are often used interchangeably. However, an astronomical body or celestial body is a single, tightly bound, contiguous entity, while an astronomical or celestial object is a complex, less cohesively bound structure, which may consist of multiple bodies or even other objects with substructures. Examples of astronomical objects include planetary systems , star clusters , nebulae , and galaxies , while asteroids , moons , planets , and stars are astronomical bodies. A comet may be identified as both

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1584-405: Is a neutron star. This system is classified as a low-mass X-ray binary (LMXB); the neutron star is roughly 1.4 solar masses , while the donor star is only 0.42 solar masses. In the late 1930s, the presence of a very hot, tenuous gas surrounding the Sun was inferred indirectly from optical coronal lines of highly ionized species. In the mid-1940s radio observations revealed a radio corona around

1656-471: Is also remarkable for its gamma-ray and radio flares during which it becomes the brightest radio source in the Milky Way . The gamma-ray flares apparently occur in the quiet radio period before a major radio flare. During the giant radio flares, a relativistic jet has been resolved within about 14 ° of being aimed directly towards us. Cygnus X-3 shows consistent variations across all wavelengths with

1728-587: Is classified by the IAU as a small Solar System body (SSSB). These come in many non-spherical shapes which are lumpy masses accreted haphazardly by in-falling dust and rock; not enough mass falls in to generate the heat needed to complete the rounding. Some SSSBs are just collections of relatively small rocks that are weakly held next to each other by gravity but are not actually fused into a single big bedrock . Some larger SSSBs are nearly round but have not reached hydrostatic equilibrium. The small Solar System body 4 Vesta

1800-606: Is due to the reflection of solar X-rays by Saturn's atmosphere. The optical image is much brighter, and shows the beautiful ring structures, which were not detected in X-rays. Some of the detected X-rays, originating from solar system bodies other than the Sun, are produced by fluorescence . Scattered solar X-rays provide an additional component. In the Röntgensatellit (ROSAT) image of the Moon, pixel brightness corresponds to X-ray intensity. The bright lunar hemisphere shines in X-rays because it re-emits X-rays originating from

1872-413: Is fifty times less massive than the Sun", said Tsuboi. "This observation, thus, raises the possibility that even massive planets might emit X-rays by themselves during their youth!" Electric potentials of about 10 million volts, and currents of 10 million amps – a hundred times greater than the most powerful lightning bolts – are required to explain the auroras at Jupiter's poles, which are

1944-622: Is in, near to, or associated with a coronal cloud or gas at coronal cloud temperatures for however long or brief a period. A combination of many unresolved X-ray sources is thought to produce the observed X-ray background . The X-ray continuum can arise from bremsstrahlung , either magnetic or ordinary Coulomb, black-body radiation , synchrotron radiation , inverse Compton scattering of lower-energy photons by relativistic electrons, knock-on collisions of fast protons with atomic electrons, and atomic recombination, with or without additional electron transitions. Clusters of galaxies are formed by

2016-492: Is much brighter in the ultraviolet than expected. Vela X-1 is a pulsing, eclipsing high-mass X-ray binary (HMXB) system, associated with the Uhuru source 4U 0900-40 and the supergiant star HD 77581. The X-ray emission of the neutron star is caused by the capture and accretion of matter from the stellar wind of the supergiant companion. Vela X-1 is the prototypical detached HMXB. An intermediate-mass X-ray binary (IMXB)

2088-484: Is not known precisely, but this method gives possible distances to Cygnus X-3 of 3.4 kpc or 9.3 kpc . There is a small X-ray source 16 ″ from Cygnus X-3 that varies with the same period by a phase lag of about 2.7 h . This is thought to be a Bok globule at approximately the same distance as Cygnus X-3. Using molecular line emission from this object, two possible distances are found to be 6.1 ± 0.6 kpc and 7.8 ± 0.6 kpc . A statistical mean

2160-517: The Andromeda nebula as a different galaxy, along with many others far from the Milky Way. The universe can be viewed as having a hierarchical structure. At the largest scales, the fundamental component of assembly is the galaxy . Galaxies are organized into groups and clusters , often within larger superclusters , that are strung along great filaments between nearly empty voids , forming

2232-599: The Compton Gamma Ray Observatory (CGRO) is the Burst and Transient Source Experiment (BATSE) which detects in the 20 keV to 8 MeV range. QSO 0836+7107 or 4C 71.07 was detected by BATSE as a source of soft gamma rays and hard X-rays. "What BATSE has discovered is that it can be a soft gamma-ray source", McCollough said. QSO 0836+7107 is the faintest and most distant object to be observed in soft gamma rays. It has already been observed in gamma rays by

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2304-828: The Energetic Gamma Ray Experiment Telescope (EGRET) also aboard the Compton Gamma Ray Observatory . Seyfert galaxies are a class of galaxies with nuclei that produce spectral line emission from highly ionized gas. They are a subclass of active galactic nuclei (AGN), and are thought to contain supermassive black holes . The following early-type galaxies (NGCs) have been observed to be X-ray bright due to hot gaseous coronae: NGC 315 , 1316, 1332, 1395, 2563, 4374, 4382, 4406, 4472, 4594, 4636, 4649, and 5128. The X-ray emission can be explained as thermal bremsstrahlung from hot gas (0.5–1.5 keV). Ultraluminous X-ray sources (ULXs) are pointlike, nonnuclear X-ray sources with luminosities above

2376-507: The Sun located in the center of the Solar System . Johannes Kepler discovered Kepler's laws of planetary motion , which are properties of the orbits that the astronomical bodies shared; this was used to improve the heliocentric model. In 1584, Giordano Bruno proposed that all distant stars are their own suns, being the first in centuries to suggest this idea. Galileo Galilei was one of

2448-425: The galactic plane . However, there is an infrared point source at its position. Cygnus X-3 is also notable as the only microquasar firmly detected in the high energy gamma rays in the range >100 MeV . Because of the variations in emission at various wavelengths, Cygnus X-3 has been given the variable star designation V1521 Cygni. Cygnus X-3 is notable for its intense X-ray emission, but it

2520-493: The photoelectric photometer allowed astronomers to accurately measure the color and luminosity of stars, which allowed them to predict their temperature and mass. In 1913, the Hertzsprung-Russell diagram was developed by astronomers Ejnar Hertzsprung and Henry Norris Russell independently of each other, which plotted stars based on their luminosity and color and allowed astronomers to easily examine stars. It

2592-491: The protoplanetary disks that surround newly formed stars. The various distinctive types of stars are shown by the Hertzsprung–Russell diagram (H–R diagram)—a plot of absolute stellar luminosity versus surface temperature. Each star follows an evolutionary track across this diagram. If this track takes the star through a region containing an intrinsic variable type, then its physical properties can cause it to become

2664-575: The Andromeda Galaxy, using observations from the ESA's XMM-Newton orbiting observatory. 3C 295 (Cl 1409+524) in Boötes is one of the most distant galaxy clusters observed by X-ray telescopes . The cluster is filled with a vast cloud of 50 MK gas that radiates strongly in X rays. Chandra observed that the central galaxy is a strong, complex source of X rays. Hot X-ray emitting gas pervades

2736-565: The CTA 1 supernova remnant (4U 0000+72) initially emitted radiation in the X-ray bands (1970–1977). Strangely, when it was observed at a later time (2008) X-ray radiation was not detected. Instead, the Fermi Gamma-ray Space Telescope detected the pulsar was emitting gamma ray radiation, the first of its kind. Three structures around Eta Carinae are thought to represent shock waves produced by matter rushing away from

2808-460: The Eddington limit of 3 × 10 W for a 20  M ☉ black hole. Many ULXs show strong variability and may be black hole binaries. To fall into the class of intermediate-mass black holes (IMBHs), their luminosities, thermal disk emissions, variation timescales, and surrounding emission-line nebulae must suggest this. However, when the emission is beamed or exceeds the Eddington limit,

2880-568: The Goddard Space Flight Center. This interaction, called charge exchange, results in X-rays from most comets when they pass within about three times Earth's distance from the sun. Because Lulin is so active, its atomic cloud is especially dense. As a result, the X-ray-emitting region extends far sunward of the comet. The celestial sphere has been divided into 88 constellations. The IAU constellations are areas of

2952-491: The Moon one of the weakest known non-terrestrial X-ray sources. NASA's Swift Gamma-Ray Burst Mission satellite was monitoring Comet Lulin as it closed to 63 Gm of Earth. For the first time, astronomers can see simultaneous UV and X-ray images of a comet. "The solar wind – a fast-moving stream of particles from the sun – interacts with the comet's broader cloud of atoms. This causes the solar wind to light up with X-rays, and that's what Swift's XRT sees", said Stefan Immler, of

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3024-450: The Sun. After detecting X-ray photons from the Sun in the course of a rocket flight, T. Burnight wrote, "The sun is assumed to be the source of this radiation although radiation of wavelength shorter than 4 Å would not be expected from theoretical estimates of black body radiation from the solar corona." And, of course, people have seen the solar corona in scattered visible light during solar eclipses. While neutron stars and black holes are

3096-701: The Sun: the Sun's magnetic activity is in fact strongly modulated (due to the 11-year magnetic spot cycle), but this effect is not directly dependent on the rotation period. Solar flares usually follow the solar cycle. CORONAS-F was launched on 31 July 2001 to coincide with the 23rd solar cycle maximum. The solar flare of 29 October 2003 apparently showed a significant degree of linear polarization (> 70% in channels E2 = 40–60 keV and E3 = 60–100 keV, but only about 50% in E1 = 20–40 keV) in hard X-rays, but other observations have generally only set upper limits. Coronal loops form

3168-565: The ULX may be a stellar-mass black hole. The nearby spiral galaxy NGC 1313 has two compact ULXs, X-1 and X-2. For X-1 the X-ray luminosity increases to a maximum of 3 × 10 W, exceeding the Eddington limit, and enters a steep power-law state at high luminosities more indicative of a stellar-mass black hole, whereas X-2 has the opposite behavior and appears to be in the hard X-ray state of an IMBH. Black holes give off radiation because matter falling into them loses gravitational energy which may result in

3240-484: The WR component will itself almost certainly become a black hole very quickly by astronomical timescales. A supernova or possible direct collapse to a black hole is expected within a million years or so. However, modelling of the Cygnus X-3 system suggests it is most likely that the binary will be disrupted by any supernova event. The cosmic ray events from Cygnus X-3 had previously led to exotic proposals such as

3312-525: The atmosphere, allowing electric currents to flow and produce an X-ray flare, like a stroke of lightning . The absence of X-rays from LP 944-20 during the non-flaring period is also a significant result. It sets the lowest observational limit on steady X-ray power produced by a brown dwarf star, and shows that coronas cease to exist as the surface temperature of a brown dwarf cools below about 2500 °C and becomes electrically neutral. Using NASA's Chandra X-ray Observatory , scientists have detected X-rays from

3384-428: The basic structure of the lower corona and transition region of the Sun. These highly structured and elegant loops are a direct consequence of the twisted solar magnetic flux within the solar body. The population of coronal loops can be directly linked with the solar cycle , it is for this reason coronal loops are often found with sunspots at their footpoints. Coronal loops populate both active and quiet regions of

3456-399: The cluster potential well . At a statistical significance of 8σ, it was found that the spatial offset of the center of the total mass from the center of the baryonic mass peaks cannot be explained with an alteration of the gravitational force law. A quasi-stellar radio source ( quasar ) is a very energetic and distant galaxy with an active galactic nucleus (AGN). QSO 0836+7107 is

3528-409: The compact star. In neutron stars and white dwarfs, additional X-rays are generated when the material hits their surfaces. X-ray emission from black holes is variable, varying in luminosity in very short timescales. The variation in luminosity can provide information about the size of the black hole. A Type Ia supernova is an explosion of a white dwarf in orbit around either another white dwarf or

3600-543: The core of a medium mass star contracts, it causes a release of energy that makes the envelope of the star expand. This continues until the star finally blows its outer layers off. The core of the star remains intact and becomes a white dwarf . The white dwarf is surrounded by an expanding shell of gas in an object known as a planetary nebula. Planetary nebula seem to mark the transition of a medium mass star from red giant to white dwarf. X-ray images reveal clouds of multimillion degree gas that have been compressed and heated by

3672-421: The emission of radiation before the matter falls into the event horizon . The infalling matter has angular momentum , which means that the material cannot fall in directly, but spins around the black hole. This material often forms an accretion disk . Similar luminous accretion disks can also form around white dwarfs and neutron stars, but in these the infalling gas releases additional energy as it slams against

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3744-558: The fast stellar wind. Eventually the central star collapses to form a white dwarf. For a billion or so years after a star collapses to form a white dwarf, it is "white" hot with surface temperatures of ~20,000 K. X-ray emission has been detected from PG 1658+441, a hot, isolated, magnetic white dwarf, first detected in an Einstein IPC observation and later identified in an Exosat channel multiplier array observation. "The broad-band spectrum of this DA white dwarf can be explained as emission from

3816-480: The first astronomers to use telescopes to observe the sky, in 1610 he observed the four largest moons of Jupiter , now named the Galilean moons . Galileo also made observations of the phases of Venus , craters on the Moon , and sunspots on the Sun. Astronomer Edmond Halley was able to successfully predict the return of Halley's Comet , which now bears his name, in 1758. In 1781, Sir William Herschel discovered

3888-589: The galaxy cluster MS 0735.6+7421 in Camelopardus. Two vast cavities – each 600,000 lyrs in diameter appear on opposite sides of a large galaxy at the center of the cluster. These cavities are filled with a two-sided, elongated, magnetized bubble of extremely high-energy electrons that emit radio waves. The X-ray landmark NGC 4151 , an intermediate spiral Seyfert galaxy has a massive black hole in its core. A Chandra X-ray image of Sirius A and B shows Sirius B to be more luminous than Sirius A. Whereas in

3960-432: The high- density surface with high speed. In case of a neutron star, the infall speed can be a sizeable fraction of the speed of light. In some neutron star or white dwarf systems, the magnetic field of the star is strong enough to prevent the formation of an accretion disc. The material in the disc gets very hot because of friction, and emits X-rays. The material in the disc slowly loses its angular momentum and falls into

4032-521: The human eye were discovered, and new telescopes were made that made it possible to see astronomical objects in other wavelengths of light. Joseph von Fraunhofer and Angelo Secchi pioneered the field of spectroscopy , which allowed them to observe the composition of stars and nebulae, and many astronomers were able to determine the masses of binary stars based on their orbital elements . Computers began to be used to observe and study massive amounts of astronomical data on stars, and new technologies such as

4104-436: The interior of a brown dwarf is in a rapid boiling, or convective state. When combined with the rapid rotation that most brown dwarfs exhibit, convection sets up conditions for the development of a strong, tangled magnetic field near the surface. The flare observed by Chandra from LP 944-20 could have its origin in the turbulent magnetized hot material beneath the brown dwarf's surface. A sub-surface flare could conduct heat to

4176-661: The merger of smaller units of matter, such as galaxy groups or individual galaxies. The infalling material (which contains galaxies, gas and dark matter ) gains kinetic energy as it falls into the cluster's gravitational potential well . The infalling gas collides with gas already in the cluster and is shock heated to between 10 and 10 K depending on the size of the cluster. This very hot gas emits X-rays by thermal bremsstrahlung emission, and line emission from metals (in astronomy, 'metals' often means all elements except hydrogen and helium ). The galaxies and dark matter are collisionless and quickly become virialised , orbiting in

4248-530: The movements of the bodies very important as they used these objects to help navigate over long distances, tell between the seasons, and to determine when to plant crops. During the Middle-Ages , cultures began to study the movements of these bodies more closely. Several astronomers of the Middle-East began to make detailed descriptions of stars and nebulae, and would make more accurate calendars based on

4320-559: The movements of these stars and planets. In Europe , astronomers focused more on devices to help study the celestial objects and creating textbooks, guides, and universities to teach people more about astronomy. During the Scientific Revolution , in 1543, Nicolaus Copernicus's heliocentric model was published. This model described the Earth , along with all of the other planets as being astronomical bodies which orbited

4392-452: The new planet Uranus , being the first discovered planet not visible by the naked eye. In the 19th and 20th century, new technologies and scientific innovations allowed scientists to greatly expand their understanding of astronomy and astronomical objects. Larger telescopes and observatories began to be built and scientists began to print images of the Moon and other celestial bodies on photographic plates. New wavelengths of light unseen by

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4464-456: The period. Therefore, the masses of the components are not known accurately. Orbital analysis suggested that the mass of the compact object is less than 5  M ☉ , probably around 2  M ☉ . It could possibly be a neutron star but is more likely to be a black hole . The combination of a WR star and a black hole would be the only known example. While the combination of WR star and compact object would be unique,

4536-449: The quintessential point sources of X-rays, all main sequence stars are likely to have hot enough coronae to emit X-rays. A- or F-type stars have at most thin convection zones and thus produce little coronal activity. Similar solar cycle -related variations are observed in the flux of solar X-ray and UV or EUV radiation. Rotation is one of the primary determinants of the magnetic dynamo, but this point could not be demonstrated by observing

4608-401: The sky. Each of these contains remarkable X-ray sources. Some of them are galaxies or black holes at the centers of galaxies. Some are pulsars . As with the astronomical X-ray sources , striving to understand the generation of X-rays by the apparent source helps to understand the Sun, the universe as a whole, and how these affect us on Earth. Multiple X-ray sources have been detected in

4680-681: The solar surface. The Yohkoh Soft X-ray Telescope (SXT) observed X-rays in the 0.25–4.0 keV range, resolving solar features to 2.5 arc seconds with a temporal resolution of 0.5–2 seconds. SXT was sensitive to plasma in the 2–4 MK temperature range, making it an ideal observational platform to compare with data collected from TRACE coronal loops radiating in the EUV wavelengths. Variations of solar-flare emission in soft X-rays (10–130 nm) and EUV (26–34 nm) recorded on board CORONAS-F demonstrate for most flares observed by CORONAS-F in 2001–2003 UV radiation preceded X-ray emission by 1–10 min. When

4752-588: The sun. The background sky has an X-ray glow in part due to the myriad of distant, powerful active galaxies, unresolved in the ROSAT picture. The dark side of the Moon's disk shadows this X-ray background radiation coming from the deep space. A few X-rays only seem to come from the shadowed lunar hemisphere. Instead, they originate in Earth's geocorona or extended atmosphere which surrounds the orbiting X-ray observatory. The measured lunar X-ray luminosity of ~1.2 × 10 W makes

4824-648: The superstar at supersonic speeds. The temperature of the shock-heated gas ranges from 60 MK in the central regions to 3 MK on the horseshoe-shaped outer structure. "The Chandra image contains some puzzles for existing ideas of how a star can produce such hot and intense X-rays," says Prof. Kris Davidson of the University of Minnesota . Abell 400 is a galaxy cluster, containing a galaxy ( NGC 1128 ) with two supermassive black holes 3C 75 spiraling towards merger. Astronomical objects An astronomical object , celestial object , stellar object or heavenly body

4896-399: The various condensing nebulae. The great variety of stellar forms are determined almost entirely by the mass, composition and evolutionary state of these stars. Stars may be found in multi-star systems that orbit about each other in a hierarchical organization. A planetary system and various minor objects such as asteroids, comets and debris, can form in a hierarchical process of accretion from

4968-412: The visual range, Sirius A is the more luminous. Regarding Cassiopea A SNR , it is believed that first light from the stellar explosion reached Earth approximately 300 years ago but there are no historical records of any sightings of the progenitor supernova, probably due to interstellar dust absorbing optical wavelength radiation before it reached Earth (although it is possible that it was recorded as

5040-537: The wind when entering the soft state. Flares are produced during the transition to the hard state as the jets are interacting with the dense wind. Cygnus X-3 lies in the direction of the Cygnus OB2 association in the Cygnus X complex, although it is much further away. Its distance can be estimated relative to Cygnus OB2 by studying the X-ray halo produced by dust between us and Cygnus X-3. The distance to Cygnus OB2

5112-428: Was discovered on 12 June 1962. This source is called Scorpius X-1 , the first X-ray source found in the constellation of Scorpius , located in the direction of the center of the Milky Way . Scorpius X-1 is some 9,000 ly from Earth and after the Sun is the strongest X-ray source in the sky at energies below 20 keV. Its X-ray output is 2.3 × 10 W, about 60,000 times the total luminosity of the Sun. Scorpius X-1 itself

5184-536: Was found that stars commonly fell on a band of stars called the main-sequence stars on the diagram. A refined scheme for stellar classification was published in 1943 by William Wilson Morgan and Philip Childs Keenan based on the Hertzsprung-Russel Diagram. Astronomers also began debating whether other galaxies existed beyond the Milky Way , these debates ended when Edwin Hubble identified

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